Chapter

Paleokarst

pp 364-384

Paleokarst and Related Pelagic Sediments in the Jurassic of the Subbetic Zone, Southern Spain

  • Juan-Antonio Vera
  • , P. A. Ruiz-Ortiz
  • , M. Garcia-Hernandez
  • , J. M. Molina

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Abstract

Several paleokarst terranes occur in the Jurassic of the Subbetic Zone (Betic Cordillera, southern Spain). They are related to stratigraphic breaks which affected the Subbetic basin during the Carixian (Middle Liassic), earliest Middle Jurassic, and the latest Bathonian. These paleokarst surfaces have been buried by pelagic sediments. They are interpreted to be related to the temporal and local emergence of pelagic swells resulting from both listric faulting and eustatic sealevel movement.

The following criteria were used to recognize paleokarst: (1) cavity morphology, (2) speleothems partially covering cavity walls, (3) collapse breccias with speleothem-enveloped clasts, (4) laminated continental cavern sediments, (5) freshwater phreatic and vadose cements in cavity host rocks, (6) age of pelagic sediments in neptunian dikes, and (7) karstic bauxites.

A model is proposed for the evolution of the pelagic swells which includes temporal emergence. Subaerial exposure surfaces are correlated with hardgrounds and condensed sequences on some swells; all are related to stratigraphic breaks which resulted from sudden global tectonic events and/or eustatic sealevel falls. The subsequent sealevel rise caused submergence and burial, cavity filling, and finally paleokarst fossilization. The proposed model of paleogeographic evolution is applicable to other, similar Mediterranean alpine realms.